The European patent publication EP-A No. 56583 describes a process for trimerisation of a polyisocyanate, more in particular a diisocyanate, with the aid of a trimerisation catalyst, which, after the desired degree of conversion of the isocyanate has been reached, is deactivated by adding benzoyl chloride. Among the trimerisation catalysts mentioned are strong organic bases, tertiary-amine-cocatalyst combinations, Friedel-Crafts catalysts, basic salts of carboxylic acids, various alkalimetal compounds, onium compounds of nitrogen, phosphorus, arsenic, antimony, sulphur and selenium, and mono-substituted monocarbamic acid esters.
In the European patent publication EP-A No. 10589 several quaternary ammonium compounds are described as catalysts for the trimerisation of 1,6-hexanediisocyanate.
When trimers of polyisocyanates containing isocyanurate-rings obtained in this manner are applied in all kinds of coating-systems, the problem arises that the deactivating agent, for example benzoyl chloride, may also deactivate or at leat inhibit the catalyst systems commonly used for curing the coating. This is particularly true for catalyst systems on the basis of amines.